So here's what LaDonna and I did today. I couldn't access the cracked transmission to remove it, so we set up an engine lift (an old CQR, some Spectra and a 4:1 with big Harken blocks) and flipped it around. Once it was turned around, I could inspect the transmission. The tragic thing was that it was destroyed by negligence (probably from the guy who owned the boat 3 owners ago). If he'd just drained the seawater from the tranny, it would be perfect. He did drain it out of the engine so obviously he just didn't know.
Three out of four fasteners came out easy (isn't that always the case?). I attacked the fourth, frozen one with steel bits and an 'easy out' device. The last pic is of the removed tranny. I'll save the almost-new innards as spares for the new-old one I'm getting from a friend.